Pulp screen



B. c'. ROOT.

` l"PULP SCREEN. APPLICATION FILED NOV. l2, 1921.

1,438,861 Patented Dec. 12, 1922..

2 SHEETS-SHEEI I.

/c/G 5 /Wm/or BfC. HOUT. PULP SCREEN. APPLxcATloN FILED Nov. 12.1921.

Patented Dec. 12,1922.

2 sHEETs-sHEm 2 vProvince of Quebec and Bominon Eid i Patented Een. l2, 1922.

are

\ y kfaire ver: 5^: V11 p, it rt BERTWE'LL C. ROOT, 0F MONTREAL? QUEBEC, GANADA, ASSIGNR `lO YDEAUL'C MACHINERY GGM'EANZ LIMITED,

or Mon-rennt, canaria.

PULP SCREEN.

application area now/@inter 12, 1921.

To all 1o/tom.. t may concern.'

Be it known that L Bnlrlwnnn C. Roer, a citizen of the United States of America., resident of the city of Montreah in the of Canada, have invented certain new and useful improvements in Pulp Screens, of which vthe following is a full7 clear, and exact descri ption of the invention.

This invention relates to in'iprovernents in pulp screens and particularly to coarse or sliver screens, and the object of this invention is to provide a screen ofsimplmdurable, and inexpensive construction which will operate in a highly e'liicient manner.

IThe device comprises a screen drum formed of perforated plates, mounted between circular end plates. The drum is revolubly mounted by hollow trunnions between end plates which are suitably braced apart in a pi A sliver trough is provided at an incline within the drum. Spray pipes are provided within the drum to wash the same and to wash the trough ln the drawings which vention, Figure 1 is an end elevation of the device; i t

Figure 2 is a side elevation with part of the drum broken away;

Figure 3 is a section on Figure 2. n t

Referring more particularly vto the drawings, '11 designates 'a pit constructed preferably of concrete and having in the bottom thereof a sump 12'and at one end an eXtension 13 of less depth than the pit. kl pair of end plates 14 are mounted in the pit at the line 3-3 g opposite ends thereof, and are held a fixed.

distance apart by tie-rods 15 and spacers 16. These end plates form supports for the screen drum, and to this end each plate is provided with a bearing portion 17 provided with a removable cap 18 to permit insertion and removal of a drum without disturbing the end plates 14.

The screen drum comprises a pair of similar circular end plates 19 each having a centrally disposed hollow neck or trunnion 2O adapted to rest in a bearing 17. The end plates 19 are connected by screen plates 21 of any suitable construction` The interior of the drum is provided with a plurality of longitudinally extending troughshaped transporting plates or flanges 22. These plates are preferably' arranged. te be :the descending side.

illustrate the in-` seriai no. 514,835.

concave side up on `the ascending side of the drum and therefore concave side down on @ne or both of the provided with a toothed circular driving ring 23 to mesh with `one or moredriving pinions 24 rigidly mounted in a driving shaft 25 journalled in the end plates 111-. As will be clearly seen inlfig'- ure 2, the bottom of the pit extension i3 is about on a level with bottom of one of the drum necks 2l). The end of the druni adjacent the pit extension 13 is the inlet end. The end plate 14 at the inlet end of the drum`r carries a bracket 26 extending through the neck and a short `distance into the drum. This bracket supports the upper end of an inclined sliver trough 27 which end plates is or are `passes lengthwise and projects through the ing into the drum, preferably through the inlet neck and branching into spray pipes 29 and 30. The pipe 29 is preferably located externally of the trough and adapted to spray the ascending side f the drum, 'while the other pipe 30 is preferably located within the trough and'adapted to spray the upper part of the drum, directly over the trough. A third spray pipe 31 is provided extending longitudinally and externally of the drum. A hood 32 of slightly greater width than lthe trough 27 is interposed between the spray pipe 3l and the drum, over the trough7 to avoid conflict between the sprays from the pipes 30 and 31. l

rlhe operation of the device is as follows: Pulp from digestors or grinders is fed into the pit extension 13, and runs from this extension through the drum neck into the drum itself in the usual manner. The drum is rotated and the pulp becomes spread over the inner surface thereof, the transporting plates 2Q serving to ensure that a large part of the surface of the drum is coated and active. These transporting plates also serve to hold slivers. bark fragments and other undesirable matter which has been separated from pulp, against falling back into pulp in the bottoni of the drum. The thin and finely ground portion of the pulp passes through 'the mesh of the screen 21 into the pit, from which it may be easily drained by reason` y Which would yWould otherwise be .int-'o the trough portion 18 ofthe removal oit of the sump. The slivers, bark, etc.` which Will not pass through the screens either adhere to the inner surface 'thereof or are caught by the transporting plates and carried to the upper part of the drum. lWater sprays trointhe pipe 29 Wash the inner surtace of the drums, and usually sweep slivers adhering' to the saine into the ascending transporting plates which serve to carry the slivers to a point over the trough 2T. These sprays serve also to Wash troni the slivers pulp adhering thereto and to drive the pulp through the inesh ot the screen These clearly defined sprays .will remove pulp not be dislodged by incre bathing of the screen with a quietly lloiving stream of Water. and therefore their use results in the recoverj of much pulp which discarded with `the slivers and lost. l/Vater sprays from the pipe 30 again Wash the inner surface of the screens, and also Wash slivers oil? the. transporting platea so that these slivers7 etc. 'tall 27, through which they are floated,v or Washed by `the current or' water which falls baclrinto 'the trough from the drum, and are thus discharged beyond the pit. Water from the spray pipe `3l Hows over the hoodl 32 and ,vashes the exterior ot the screens to reinovo any pulp which has passed through,and is clingingto the screens, and .vashessaine into the pit.

According to the present invention the expensive iron vats generallyy einplol l are eliminated by the provision of a eorerete pit and means to Vrotatably support the soi-een drum therein. This'lneans that the pur- Chaser neither buys nor pays ltransportation 0n a great amount of iron but provides the pit or vat locally at a minimum oi2 ci t The arrangement of stays between the end plates 14- provides a-r'igid and inexpensive support for the drum Which may be easilj,r assembled or taken apart. The removable end plates permit ot easy the screen drum as a Whole, The trough may be readily removed by lifting its upper end ott lthe bracketfb and sliding` it out of the back end ot the drum.

l. claim is choked, The, hood 32 not only prevents conflict of sprays from the pipes 30 :ruil

3l but also receives the inipaet of jets troni the pipe 3L so that the Water flowing over the plateBQ triclrles gently over the inside ot' the druro and Washes pulp oli the outer surface thereof.3 fi'hout any danger ol Wash` ing' the pulp bach into the drum. v

` Having thusy described in); invention4l what beer ing plates in said vat, stay bo and spacers holding` said bolts rigidly in spaced relation and a screen drinn rotatably supported by said plates. y

2. A device accordinlg;` to 4claim one in which each plate is formed in two seoarable parts Aforming between them u beariA '5.

3. ln a pulp screening device., a rotar` screen drum, internal transporting pl carried by said drum, a sl iver trough i l. In a pulp-screening device the drum, pair of spray pipes Within the druni, one oi" said pipes being located eX- ternally of the trough, and arranged to direct jets of `Water against the ascending` side oit the dru'in', to Wash porting plates and the second Aot said pipe` being disposed Within the trough vand arranged to d. jetsoj ,vater against the Vie dru'no and the vtransp@rting i the trough to Wash slivers thereliroin into the trough.

4f. ln a pulp screening device.` a rotatable screen druinnv a sliver trough therein, a spray pipe Within the druni ranged to direct jets of Water against the inner sur'frue oit the druni above the troughs a second spray.' pipe disposed externally oil the drum and ranged to direct` 'iets oit Water toward the drunn ane a hood interposed between said second spray pipe and the drum above Jdie trough.

f In witness my hand.

whereof, l have herenntoy set spray pipes ensures sliver-s on to the transl 

